8BQ5 — Power Pentode, Noval | Tubeofile

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8BQ5

Power Pentode — Noval

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Known Equivalents & Substitutes

No known equivalents. If you know of any, use the ⚑ Report Issue button above.

Similar Tubes (Not Drop-In Compatible)

6BQ5

American designation for EL84 — same electrical characteristics but 6.3V heater

8GK6

Similar 8.4V heater pentode listed as equivalent in Brans

EL84

Same electrical characteristics but 6.3V heater — not a drop-in in 8.4V series-string circuits

UEL84

100mA series-string heater version of EL84 — different heater voltage

Electrical Specifications

Section 1 — Pentode

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)300V

Screen Voltage (max)Screen Voltage (max)300V

Anode Dissipation (max)Anode Dissipation (max)12W

Screen Dissipation (max)Screen Dissipation (max)2W

Cathode Current (max)Cathode Current (max)

Notes

8.4V / 0.45A heater for series-string TV receiver heater chains. Electrically identical to EL84/6BQ5 in all other respects.
Not interchangeable with EL84/6BQ5 without heater circuit modification.
Brans Vademecum lists equivalents: 16GK6, 29GK6, 6BQ5, 6GK6, 6P15, 7189A, 8GK6, EL172, EL20, EL22, EL84 — many of these have different heater voltages and are not direct drop-in replacements.

Pin Layout — Noval

1Internal Connection

2Control Grid (g1)

3Cathode (g3 internally connected)

Socket-Compatible Tubes ⚠ Not electrically compatible

6P43P EL84 EL85 PL84 UEL84

65mA

Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max)100V

Max Grid ResistorMax Grid Resistor (cathode bias)1MΩ

Typical Operating

Anode Voltage (typical)Anode Voltage (typical)250V

Screen Voltage (typical)Screen Voltage (typical)250V

Grid 1 Bias VoltageGrid 1 Bias Voltage-7.3V

Anode CurrentAnode Current48mA

Screen CurrentScreen Current5.5mA

Anode ResistanceAnode Resistance38,000Ω

TransconductanceTransconductance11.3mA/V

Cathode Resistor (self-bias)Cathode Resistor (self-bias)135Ω

Output

Output PowerOutput Power5.7W

Load ImpedanceLoad Impedance4,500Ω

Capacitances

Grid-to-Plate CapacitanceGrid-to-Plate Capacitance0.5pF

Grid-to-Cathode CapacitanceGrid-to-Cathode Capacitance10.8pF

Anode-to-Cathode CapacitanceAnode-to-Cathode Capacitance6.5pF

Section 2 — Triode Strapped

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)300V

Anode Dissipation (max)Anode Dissipation (max)12W

Cathode Current (max)Cathode Current (max)65mA

Typical Operating

Anode Voltage (typical)Anode Voltage250V

Grid 1 Bias VoltageGrid 1 Bias Voltage-9.5V

Anode CurrentAnode Current35mA

Anode ResistanceAnode Resistance2,000Ω

TransconductanceTransconductance8.5mA/V

Amplification Factor (μ)Amplification Factor (μ)17—

Cathode Resistor (self-bias)Cathode Resistor (self-bias)270Ω

Output

Output PowerOutput Power1.95W

Load ImpedanceLoad Impedance3,500Ω

Heater

Heater VoltageHeater Voltage8.4V

Heater CurrentHeater Current0.45A

4Heater

5Heater

6Internal Connection

7Anode (Plate)

8Internal Connection

9Screen Grid (g2)